"Life-event triggers." Are you getting married? Soon to have a baby? Beckett reports that one company, Experian, updates its list of expectant and new parents "weekly."

Salary and wages: "A subsidiary of credit reporting company Equifax even collects detailed salary and paystub information for roughly 38 percent of employed Americans, as NBC news reported," Beckett writes. But, she adds, "that if a mortgage company or other lender wants to access information about your salary, they must obtain your permission to do so."

2. Retail information

One company, Datalogix, keeps track of consumer spending on store loyalty cards amounting to $1 trillion at more than 1,400 brands. Datalogix did not respond to ProPublica's inquiries for further details.

In one study, Beckett reports, Walt Disney explained that shared a person's name, address, and purchase history with other companies including Honda and Dannon, though a spokeswoman said that the data sharing was limited to the context of a specific joint promotion.